Neanderthal cousins: Artists reconstruction of a Denisovan girl based on the combination of skeletal and DNA evidence.This is the first in a series on the Aboriginal peopling of New England drawn from the introductory course I have been running on New England's history.
We all carry our ancestry within us,
imprinted in our DNA. We all know this in part because it provides the base for
the increasingly popular ancestry DNA tests. What is perhaps less recognised is
the way in which the science of genomics has totally transformed our knowledge
of the deep human past.
Genomics, an interdisciplinary field of
biology, focuses on the structure, function, evolution, mapping, and editing of
genomes. A genome is an organism's complete set of DNA, including all of its
genes.
Genomics allows us to map and compare DNA
from even ancient specimens. It allows us to map changes over time, and to
estimate when certain changes might have taken place. This has resulted in a
knowledge explosion.
The mysterious Denisovans
are a case in point.
Denisova
Cave lies in the Altai Mountains in south-central Siberia near the border with
Kazakhstan, China and Mongolia.
In 2010, a
Russian team announced that the DNA analysis of a juvenile female finger bone
from the site had revealed a new hominin species that they named the Denisovans
after the cave. The Denisovans were cousins to the European based Neanderthals,
but had separated from them several hundred thousand years before.
This was
remarkable enough, but more was to follow. DNA analysis of other remains and of
modern human populations suggested that the Denisovans were widely spread
across Asia with two distinct lines, one in East Asia, a second in South East
Asia.
Further,
the results show that the Denisovans overlapped with the Neanderthals at
Denisova and with both Homo Erectus and anatomically modern humans in East and
South East. The widespread nature of the Denisovan trace in dispersed
anatomically modern human populations suggests extensive interbreeding with
multiple Denisovan populations.
The DNA
analysis also revealed that in their long journey out of Africa to the ancient
continent called Sahul, the ancestors of the Papuans and Australian Aborigines had
met and mated with the Denisovans.
This mating
probably took place in what is now South East Asia close to Sahul. However, the
trace is so strong among Papuans that it raises the possibility that the
Denisovans may have lived in Papua or nearby islands until as recently 30,000
years ago.
This date
is well within the period of Aboriginal occupation of Sahul. It raises an
intriguing question: if the Denisovans were in Papua, then the northern
extension of Sahul, did they penetrate further south into what is now the
Australian continent?
Note to readers: This post appeared as a column in the Armidale Express Extra on 25 March 2020. I am repeating the columns here with a lag because they are not all on line outside subscription. You can see all the Belshaw World and History Revisited/History Matters columns by clicking here for 2009, here for 2010, here for 2011, here for 2012, here for 2013, here for 2014, here for 2015, here for 2016, here 2017, here 2018, here 2019, here 2020
No comments:
Post a Comment